Helicobacter pylori continues to afflict a large percentage of the human population worldwide, causing diseases ranging from gastritis and ulcers to cancer. This organism remains difficult to cultivate without serum, and little is known about serum components beneficial for H. pylori growth. Our preliminary data indicate that ceruloplasmin (cp) from human or bovine serum and at least one other unidentified serum protein are responsible for augmenting growth. We hypothesize that cp and another protein synergize to supply iron to H. pylori or protect the bacterium from oxidative stress. The specific aims of this proposal are to: 1. Confirm the identity of ceruloplasmin as one of the serum proteins augmenting H. pylori growth. 2. Determine the mechanism of ceruloplasmin effect on H. pylori growth. 3. Identify the other serum protein(s) required for augmentation of H. pylori growth. Various biochemical tests and cloned sources of ceruloplasmin homologs will be used to achieve aim 1. Aim 2 will involve examination of iron uptake and resistance to oxidative stress in the presence of ceruloplasmin. We will accomplish aim 3 by using advanced mass spectroscopic analysis to identify proteins present in or absent from serum fractions, followed by testing of purified proteins. Results from this study may have wide-ranging impacts on the study of H. pylori and other fastidious bacteria. Although many studies have addressed adhesion factors important for colonization, little is known about other host factors required for H. pylori growth and pathogenesis. Furthermore, numerous other pathogenic species remain difficult or impossible to cultivate in vitro. A more complete understanding of serum proteins interacting with bacteria could lead to advancements in cultivation of other organisms as well.